1. Technical Field
The present invention relates to a display device provided with microcapsules and an electronic apparatus including the display device.
2. Related Art
Hitherto, electrophoretic display devices, each of which includes an electrophoretic dispersion liquid containing a liquid-phase dispersion medium and electrophoretic particles and utilizes the phenomenon in that the distribution state of the electrophoretic particles changes in the presence of an applied electric field, thus changing the optical properties of the electrophoretic dispersion liquid, have been known (for example, refer to Japanese Unexamined Patent Application Publication No. 9-185087 [Patent Document 1]). In such electrophoretic display devices, since a backlight is not required, the cost can be reduced and the thickness can be decreased. Moreover, the electrophoretic display devices provide a wide angle of view and a high contrast, and also have memory effects in terms of display. Therefore, the electrophoretic display devices have been receiving attention as a next-generation display device.
Furthermore, in a known electrophoretic display device, an electrophoretic dispersion liquid is encapsulated in microcapsules, and the microcapsules are sandwiched, for example, between a transparent substrate provided with a transparent electrode which serves as a common electrode and a substrate provided with pixel electrodes. Encapsulation of the electrophoretic dispersion liquid in microcapsules is advantageous in that it is possible to prevent the dispersion liquid from flowing out during the fabrication process of the display device, and it is possible to decrease sedimentation and aggregation of the electrophoretic particles.
In such an electrophoretic display device provided with microcapsules, as a method for providing conduction between the transparent electrode and the substrate, a technique of using a conductive material including a resin and conductive particles incorporated therein is generally employed. As the conductive material, a conductive paste including a resin, such as epoxy, and conductive particles, such as metal particles, e.g., silver, or carbon particles, are incorporated therein, or a conductive sheet produced by forming the conductive paste into a sheet is known.
When conduction is achieved between the substrates using such a conductive material, in order to prevent the occurrence of color irregularity and the like, the thickness (height) of the conductive material is set so that the distance between the substrates in the display area composed of the microcapsules is the same as the distance between the substrates at a vertically conducting portion which is conducted by the conductive material, and the vertically conducting portion is formed.
However, in the display device having the structure described above, when reliability tests, such as a high-temperature preservation test and a temperature cycling test, are performed, in some cases, separation may occur between the transparent substrate or the substrate and the conductive material due to thermal expansion and thermal shrinkage of the resin in the conductive material, resulting in defective continuity. When defective continuity occurs in such reliability tests, it is expected that long-term reliability may not be ensured when the product is in the market. Therefore, it has been strongly demanded to take measures against the problems.